This invention relates in general to electrical submersible well pumps, and in particular to a electrical submersible pump inside the riser. More particularly, the device is useful in wells currently using conventional gas-lift.
Devices have been proposed to boost the pressure and flow in a producing well. An example of such a device is described in U.S. Pat. No. 5,044,440, which utilizes an underwater separating, compressing, and pumping station that sits on the ocean floor to boost the flow of a well or a number of wells. Another device, described in U.S. Pat. No. 5,755,288, is a downhole gas compressor assembly that includes a separator, a compressor, and a pump that is located at the production zone by the perforations in the well.
Offshore wells are now being drilled in very deep water. Delivering the produced well fluid from the top of a well at the sea floor, through thousands of feet of riser requires extensive energy. Gas lift has been proposed, but this requires a high injection pressure and a large compressor on a production platform at the surface.
According to the present invention, a submersible pump of the type that would normally be applied to a downhole well application can be installed within the oil production riser pipes of a composite or steel riser system above the sea floor, or any other new deepwater riser configuration. The pump could be electrically or hydraulically powered, or utilize another energy source.
The pump assembly is comprised of an intake for oil, water, and gas outfitted with a check valve to insure against reverse flow. The fluids and gases are then fed into a gas through pump or a separator and then the liquids are sent to a pump. The liquids leave the pump outlet and are sent to the surface by the riser. Gas is vented in the annular space between the riser and the production tubing.